1. Field of the Invention
The present invention relates to a halogen-free and thermal resistant composition and in particular to its application of printed circuit board, IC packaging, LED packaging, or the likes.
2. Description of the Related Art
In recent years, consumer demand for the quality and quantity of electronic products, specifically, light, thin, short, and small products, has been accelerated by huge investments in the optoelectronic industry. One major development in electronic products is high density packaging, where tape automated bonding (TAB) and chip on film (COF) technologies applied in consumer electronics, mainframe and servers, liquid crystal displays, and IC cards. Flexible printed circuit board (FBC) can be applied in notebook, the automobile industry, the telecommunication industry, and/or lead frame tapes. TAB, COF, and FBC require a solder process to adhere the electronic devices to the printed circuit board. The operation temperature in solder process may reach 288° C. or above, in this situation, the thermal resistant packaging material can improve the dimensional stability and reduce inaccurate alignment of the circuits. Additionally, the increase of layers in integrated circuit will raise the device temperature when electrified, such that the adhesive and the packaging materials with high Tg are needed to improve the manipulation stability of the electronic device.
Conventionally, the adhesive agent used in multi-layered flexible printed circuit board or multi-layered TAB is acrylic resin or epoxy resin, however, their thermal resistant and chemical resistant properties are poor than polyimide (PI). For strengthening thermal resistant and chemical resistant properties of the epoxy resin, bismaleimide is blended thereto. The blending resin is brittle and then further needs rubber to enhance toughness. Unfortunately, this mixture cannot be coated homogeneously due to phase separation.
For solving the described problem, the inventor previously patented Taiwan patent No. 466265 in 1998. In this patent, the adhesive agent composition comprises bismaleimide, barbituric acid, and epoxy resin. The polymerization of the composition requires a high boiling point solvent such as γ-butyrolactone that cannot be fully removed after polymerization. The residue solvent will degrade the quality of the electronic devices it is being used in.